1. Field of the Invention
The present invention relates to a safety belt retractor adapted for use in a motor vehicle, and more particularly to a safety belt retractor provided with an emergency locking mechanism for fastening the driver or passenger when the vehicle moves with a speed change exceeding a predetermined value.
2. Description of the Prior Art
There are already proposed various safety belt retractors provided with such emergency locking mechanisms, but such retractors inevitably require complicated and expensive parts with an elevated number of component parts in order to achieve precise and secure emergency locking function.
In the prior art of the emergency locking mechanism there are proposed and already in actual use a locking mechanism functionable by sensing the acceleration or deceleration of the vehicle through the extracting acceleration of a webbing as disclosed for example in the U.S. Pat. No. 3,489,799 and a locking mechanism functionable by sensing the acceleration or deceleration of the vehicle directly for example by a pendulum as disclosed for example in the U.S. Pat. No. 3,758,044. Also for a securer locking of the safety belt retractor there is already employed a retractor provided with the above-mentioned two mechanisms as disclosed in the U.S. Pat. No. 4,083,511, but the presence of two complicated mechanisms renders the entire retractor larger and also expensive due to the elevated number of component parts required.